To service the McLaren F1 supercar, McLaren needs a Compaq LTE 5280 laptop which hasn’t been manufactured in about 20 years http://www.theverge.com/2016/5/3/11576032/mclaren-f1-compaq-laptop-maintenance. The laptop has a special CA (“Conditional-Access”) card, and

"The CA card is an interface between the laptop software (which is DOS-based) and the car."

.. the CA card was used as custom hardware as part of an integrated system for security and copy protection.

In other words, this is part of a system to ensure that nobody but McLaren can access the car software. Their attempt at vendor lock-in has led to vendor lock-in being imposed on them.